Green tea conversion using tannase and natural tea enzymes

Claim 2

A process for preparing black tea from green tea comprising the steps of a. preparing a hot water extract from green tea, b. adding tannase to the extract within a temperature range in which the tannase is active and at a level of at least one enzyme unit per gram of tea solids, c. converting the green tea extract to black tea under aerobic conditions in the presence of natural tea leaf enzymes, and d. dehazing and polishing the extract, said addition being for a time sufficient to substantially reduce the amount of tea cream produced in the conversion of green tea extract to black tea.

Claim 3

A process for preparing black tea from green tea comprising the steps of a. preparing a hot water extract of green tea, b. contacting the hot water extract with tannase within a temperature range in which it is active, the tannase being immobilized on a support, c. converting the tannase treated extract to black tea under aerobic conditions by bringing the extract into contact with natural tea leaf enzymes immobilized on a support, and d. dehazing and polishing the extract, said contacting being for a time sufficient to substantially reduce the amount of tea cream produced in the conversion to black tea.

Claim 4

A process for preparing black tea from green tea comprising the steps of a. preparing an aqueous homogenate of green tea leaf, the ratio of water to tea leaf solids being within the range of about 3:1 to about 10:1 by weight, b. adding tannase to the homogenate within a temperature range in which the tannase is active and at a level of at least one enzyme unit per gram of tea leaf solids, c. converting the green tea solids to black tea in the presence of natural tea leaf enzymes by controlled addition of increments of hydrogen peroxide thereto, and d. separating the leaf residue from the aqueous extract, said addition being for a time sufficient to substantially reduce the amount of tea cream produced in the conversion to black tea.

Claim 5

A process for preparing black tea from green tea comprising the steps of a. preparing an aqueous homogenate of green tea leaf, the ratio of water to tea leaf solids being within the range of about 3:1 to about 10:1 by weight, b. adding tannase to the homogenate within a temperature range in which the tannase is active and at a level of at least one enzyme unit per gram of tea leaf solids, c. converting the green tea solids to black tea by aerating the tea leaf homogenate while adding increments of hydrogen peroxide in the presence of natural tea leaf enzymes, and d. separating the leaf residue from the aqueous extract, said addition being for a time sufficient to substantially reduce the amount of tea cream produced in the conversion to black tea.

Claim 6

A process of converting green tea to black tea comprising the steps of a. comminuting fresh tea leaf under conditions which retain the natural tea leaf enzyme, b. suspending the comminuted leaf in water, the ratio of water to tea leaf material being within the range of 3:1 to 10:1 by weight, c. adding tannase to the tea leaf suspension at a level of about eight enzyme units per gram of dry weight of tea leaf tissue at 45* C while maintaining gentle agitation, d. adjusting the temperature of the suspension to 25* C and converting the green tea to black tea in the presence of the natural tea enzymes by sparging the suspension with air, e. separating the leaf residue from thE extract, and f. dehazing and polishing the extract, said addition being for a time sufficient to substantially reduce the amount of tea cream produced in the conversion of green tea to black tea.

Claim 7

The process of claim 7, where the polished extract obtained in (f) is dried to provide a tea powder.

Claim 8

A process of preparing black tea extracts from green tea comprising the steps of a. preparing an aqueous homogenate of finely divided green tea leaf, the ratio of water to tea leaf solids being within the range of about 3:1 to about 10:1 by weight, b. adding tannase to the homogenate within a temperature range in which the tannase is active, and at a level of at least one enzyme unit per gram of tea leaf solids, c. converting the green tea solids to black tea under aerobic conditions in the presence of natural tea leaf enzymes, and d. separating the leaf residue from the aqueous extract, said addition being for a time sufficient to substantially reduce the amount of tea cream produced in the conversion of green tea solids to black tea.

Claim 9

The process of claim 9, wherein the green tea leaf is freshly picked.

Claim 10

The process of claim 9, wherein the tannase is added at a level of from one to 16 enzyme units per gram of tea leaf solids.

Claim 11

The process of claim 9, wherein step (b) is conducted at the pH of the tea homogenate, and wherein step (c) is conducted at a pH within the range of about 4.8 to about 6.0.

Claim 12

The product of the process of claim 9.

Claim 13

The process of claim 9, wherein, following step (c), the leaf residue is separated from the extract, and the extract is dehazed and polished.

Claim 14

The process of claim 14, wherein the dehazed and polished extract is dried to provide a tea powder.